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Morphological and physicochemical changes in the myosin molecules induced by hydrostatic pressure
K Yamamoto1, Y Yoshida, J Morita
1Department of Food Science, Rakuno Gakuen University, Hokkaido.
Journal of Biochemistry
|July 1, 1994
Summary
High hydrostatic pressure causes myosin molecules to aggregate through head-to-head association, exposing hydrophobic groups and reducing ATPase activity. This pressure-induced aggregation alters myosin
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Chemistry
Background:
- Myosin is a crucial motor protein involved in muscle contraction.
- Understanding protein behavior under extreme conditions like hydrostatic pressure is vital for biochemical research.
Purpose of the Study:
- To investigate the morphological and physiochemical changes in monomeric myosin induced by hydrostatic pressure.
- To elucidate the mechanisms of pressure-induced myosin aggregation.
Main Methods:
- Exposure of monomeric myosin solutions to varying hydrostatic pressures (100-300 MPa).
- Turbidity measurements to assess molecular aggregation.
- Spectrofluorometry using 8-anilino-1-naphthalene sulfonate to measure hydrophobicity.
- Assay of myosin ATPase activity.
Main Results:
- Hydrostatic pressure induced myosin aggregation, evidenced by increased turbidity.
- Pressurization led to head-to-head association, forming oligomers, some with single heads.
- Oligomer morphology at 300 MPa resembled a 'daisy wheel' with radially extending tails.
- Increased hydrophobicity correlated with aggregation, suggesting exposure of hydrophobic groups in myosin heads.
- Myosin ATPase activity decreased concurrently with aggregation.
Conclusions:
- Hydrostatic pressure triggers aggregation of monomeric myosin via head-to-head association.
- Exposure of hydrophobic groups within myosin heads drives this pressure-induced aggregation.
- The findings suggest a role for hydrophobic interactions, potentially alongside other forces, in myosin structural changes under pressure.